It appears that neither intense cold nor extreme heat has deterred the success of a San Antonio Zoo effort to release Texas horned lizards bred in captivity into the wild.
The San Antonio Zoo began the program in 2017, raising dozens of Texas horned lizards — also known as “horny toads” — in captivity for three years before releasing 84 lizards onto a private ranch in Blanco County in 2020. Since then, the zoo has released roughly 200 more lizards into this area in an effort to combat their threatened species status.
While readying to release an additional 50 Wednesday, San Antonio zoologists were thrilled to find Texas horned lizard scat and other signs that the lizards previously released in the area are thriving — despite the freeze of 2021 and the intense heat and drought of this summer.
Andy Gluesenkamp, director of the zoo’s Center for Conservation and Research and former Texas state herpetologist, said as Texas animals, the horned lizards have proved hearty.
“Like any other wildlife, you may lose a few horned lizards in that kind of freak weather event,” Gluesenkamp said. “But if so, it was on the light side. We found fresh lizard scat here just a few months after the freeze.”
With the help of two lizard-sniffing canines, who can point out live lizards, scat and shed skin, Gluesenkamp and his team collected scat samples Wednesday to send to Texas Christian University’s biology professor Dean Williams. Gluesenkamp has been working with Williams to track the status and health of the released lizards.
“It’s very easy to identify Texas horned lizard scat, because it’s entirely made up of ant body parts usually,” Gluesenkamp said. Texas horned lizards eat mostly harvester ants, but also enjoy termites as well, he said. Scat is a very good sign — “What [Williams and his students] discovered was that the scat samples represented 10 times more individuals than [we] observed.”
Since 2017, Gluesenkamp and his team have worked painstakingly to help restore the lizards back to their former numbers. Loss of habitat, fire ants and a decline in harvester ants have contributed to the lizard’s disappearance from most of its former territory east of Interstate 35, according to Gluesenkamp.
Gluesenkamp and Williams’ research has allowed the two scientists and their teams to track even individual lizards. Williams’ lab has genotyped all of the zoo’s lizards prior to their release and can track it from their scat or skin samples, Gluesenkamp said.
“So not only can we track [scat] to those individual lizards, it then that allows us to say, ‘Well maybe there’s a secret sauce here’ — maybe certain groups do better because their parents had a slightly different color pattern or a different cold tolerance or something.”
Gluesenkamp attributed the success of the program to the zoo’s donors. Over the course of the last five years, the program has spent about $1 million in grants and donations toward these efforts to reintroduce Texas horned lizards into the wild, he said.
“I can say with pride to our donors, ‘This is where your money goes,’” he said.